The purpose of this proposal is to inhibit telomerase activity by the use of ribozyme technology. Telomerase is an important target because most cancer cells have telomerase, but most normal cells do not. Hence, if one could design an effective anti- telomerase agent, it might be effective against many forms of cancer cells, but have minimal effects on normal cells. Of the multiple components of the human telomerase complex thus far cloned, the presence of telomerase activity in malignant cells is due principally to the induction of the catalytic subunit, hTRT. Hence the target of our ribozyme attack will be the catalytic subunit of telomerase.